An arrangement for supplying an anesthetic dispensing apparatus with a liquid anesthetic is disclosed in U.S. Pat. No. 4,825,860. A modularly configured supply vessel for liquid anesthetic is connected to the anesthetic dispensing device of an anesthetic apparatus in that the supply vessel is inserted into the anesthetic dispensing device along a guide. The supply vessel is provided with an identifier which makes it possible for the user to determine which anesthetic is supplied to the anesthetic apparatus from the supply vessel utilized. Furthermore, a fill device, which is specific to the anesthetic, and a fill level indicator are located on the supply vessel. In the coupled state of the supply vessel, the anesthetic reaches the anesthetic dispensing device via a check valve and a tapping stub. The tapping stub is part of the anesthetic dispensing device and, when coupling in, opens the check valve located in the supply vessel so that the anesthetic can flow into the anesthetic dispensing device. A metering device for the anesthetic is located within the anesthetic dispensing device, for example, in the form of a metering pump with which the desired quantity of anesthetic is made available.
It is disadvantageous in this known arrangement that, when changing the anesthetic, the previous anesthetic is still metered for a certain time because it is still located in the connecting line between the tapping stub and the metering device; whereas, the anesthetic, which is next to be applied, is available only after the residual quantity is consumed.
In the article of J. B. Cooper et al entitled xe2x80x9cA New Anesthesia Delivery Systemxe2x80x9d, Anesthesiology 49, pages 310 to 318 (1978), an anesthetic system is known wherein liquid anesthetic is metered by means of a metering valve from an exchangeable supply vessel into the breathing loop of an anesthetic apparatus. The supply vessel is seated in a socket connection of the anesthetic apparatus and is connected thereby to the metering valve. When changing the anesthetic, the supply vessel disposed in the apparatus is removed by means of a lifting device and is exchanged for another.
In this known system, it is disadvantageous that residual quantities of the previous anesthetic remain in the apparatus when changing the anesthetic. Furthermore, when the metering valve malfunctions, no metering of anesthetic is possible because the metering valve is mounted fixedly on the anesthetic apparatus.
It is an object of the invention to improve an arrangement of the kind described above so that, when changing the anesthetic, the new anesthetic is directly available for metering and that an exchange is possible in a simple manner when there is a malfunction of the metering valve.
The arrangement of the invention is for supplying a medical apparatus with an anesthetic. The arrangement includes: a supply vessel for holding the anesthetic in liquid form; a metering device for metering the anesthetic and the metering device being connected to the supply vessel so as to form a module therewith; a receptacle on the apparatus for receiving and accommodating the supply vessel; and, a connector between the metering device and the receptacle.
The advantage of the invention is essentially that the metering device and the supply vessel are connected to each other in a module because of the arrangement of the metering device directly on the supply vessel and, in this way, the metering device is exchanged along with the supply vessel when exchanging the latter. The metering device executes a blocking function for the supply vessel as well as a metering function for the anesthetic located in the supply vessel. For this reason, only the anesthetic, which is located in the connected supply vessel, is outputted without this leading to a mixing of the liquid anesthetic when changing the supply vessel. When there is a defect of the metering device, it is a further advantage that only a new supply vessel must be seated in the anesthetic apparatus without a significant interruption of the operation of the apparatus. Maintenance of the metering device is also significantly simplified by the attachment in accordance with the invention because the metering device is freely accessible from all sides and, therefore, maintenance measures can be executed simply and rapidly.
A further advantage of the arrangement according to the invention is that a check valve is mounted on the supply vessel because the interface to the anesthetic apparatus is located behind the metering device and, in this way, the metering device can realize the blocking function in addition to the metering function.
Coupling of the supply vessel to the vessel receptacle of the anesthetic apparatus takes place via a connecting element. The connecting element is either connected to the output of the metering valve so that the anesthetic reaches the anesthetic apparatus directly via the connecting element or it is located on the supply vessel in the region of the anesthetic outputted via the metering valve. The inclusion of the supply vessel in the connecting element affords the advantage that a larger surface is available for the adaptation and, in this way, the connecting element has greater mechanical stability. This is so because the connecting element must be designed for the inherent weight force of the anesthetic volume stored in the supply vessel in the context of strength and tightness characteristics. In addition, possible bending and torsion torques apply. With a connecting element configured in this manner, the supply vessel can be coupled especially simply to the respiratory gas conducting parts of the anesthetic apparatus so that the anesthetic, which is outputted by the metering device, can be mixed directly with the respiratory gas flow. The connecting element can also include a combination of the supply vessel and the metering device so that, at the output of the metering device, the mechanical adaptation is undertaken via the supply vessel in that the supply vessel surrounds the output of the metering device in the form of a sleeve.
According to a feature of the invention, a storage volume is connected downstream of the metering device and the connecting element is located downstream of the storage volume.
In a practical manner, the supply vessel includes a pressurized gas connection via which the interior space of the supply vessel can be charged with a defined pressure. In this way, a defined prepressure is generated for the metering device, for example, for an injection valve. A venting of the supply vessel is also possible via the pressurized gas connection. The arrangement according to the invention is especially advantageous in combination with the metering of anesthetics having a low boiling point because an adequate prepressure can be adjusted for the metering because of the vapor pressure of the anesthetic. A pressure buildup in the supply vessel can be generated by warming the anesthetic with a heater.
In a practical manner, the metering component is attached at the lowest point of the supply vessel so that the entire anesthetic disposed in the supply vessel can be withdrawn. This positioning is suitable for the metering of liquid anesthetic.
The metering component is disposed above the maximum anesthetic fill level in order to make a saturated anesthetic vapor available.
In an advantageous manner, the metering component is configured as a metering valve in the form of an injection valve as known from motor vehicle technology. A large variation of metered anesthetic quantity is realized by controlling the injection valve via a pulse-pause modulated control signal. The injection valve receives electrical control signals from a central control unit with which the injection valve is opened or closed. As an alternative to an injection valve, a micrometering pump can also be utilized.
Pneumatically controlled metering valves can be used as an alternative to electrically operated valves.
The connection is advantageously provided as a pin-and-socket connector, for example, in the form of a rapid connector, as is known from connections for fluid lines. In this way, the part of the connector which is connected to the supply vessel can comprise a hollow elongated body; whereas, a bore configured therefor can be provided on the vessel receptacle as a coupling receptacle. The connector can also be configured as a peripherally extending sealing surface between the supply vessel and the vessel receptacle. The metered anesthetic is outputted to the vessel receptacle in a region enclosed by the sealing surface.
An advantageous use of a supply vessel for liquid anesthetic configured as an insert module comprises connecting this supply vessel with a metering device as a modular unit in order to supply anesthetic to a medical apparatus in correspondence to a metering input.